The presence of undesirable bacterial contamination in food products intended for consumption is of significant concern to manufacturers, farmers, packagers, food distributors, wholesalers, retailers, consumers, and to worldwide public health. A particularly worrisome concern is bacterial contamination in packages containing food products for human consumption. The United States boasts of the safest food in the world; however, each year approximately one in four individuals suffer from a food borne illness and some 5,000 die from something they have eaten. According to the Center for Disease Control and Prevention, each year in the United States, 76 million people contract some kind of food borne illness, 325,000 are hospitalized and 5,000 fatalities occur due to contamination of consumed food. In Third World countries it has been estimated that bacterial contaminated food and water kills over two million children each year. Despite those numbers, most food borne infections are undiagnosed and unreported.
Packaging of perishable and edible food products may be susceptible to undesired and undetectable bacterial growth during each stage in the food chain from harvest to consumption. Minimal levels of bacterial contamination (bacterial load) of food is deemed acceptable in food for consumer use. Indeed, regulatory agencies such as the FDA have established limits on bacterial load permitted in the food. Nevertheless, it is very hard to determine if bacterial growth in food alters the bacterial level of the food to unacceptable levels. Food initially safe for consumption may be altered by undetected bacterial growth due to poor handling, improper storage and other factors. At all points in the food chain, it would be of great benefit if there was an unmistakable means to determine that there has been unacceptable bacterial growth occurring on the food.
Still further, bacterial contamination of wounds can lead to serious infection, illness, and even death if the contamination is unnoticed and untreated for even a relatively short period of time. Often times, bacterial infection is first detected by the presence of inflamed red skin around a wound site. Visualization of the wound by skin redness is often at a point where the infection has significantly progressed within the diseased patient.
Examples of such wounds are those generated by use of central venous catheters, cannulae, and related medical devices (hereafter “catheters”) which are inserted and maintained through the skin. As is apparent, catheters are used on a variety of patients, usually in a hospital setting. These catheters provide secure access e.g., into a patient's blood vessel and allow for the safe administration of fluids and drugs into the patient or the removal of fluids from the body.
Wounds of all nature carry an inherent risk of bacterial infections. In addition to intentionally created wounds such as those described above, other wounds susceptible to infection include abrasions, burns, surgical incisions, injection sites, and the like.
For example, catheter insertion into the body can cause serious complications. Specifically, catheter related bloodstream infection (CR-BSI) is a serious and potentially life-threatening complication when catheter insertion sites into blood vessel lumen become infected with bacterial microorganisms. Conventional state of the art care now requires that these insertion sites be covered with a wound dressing as a preventive measure against such infections.
A number of factors render such insertion sites especially susceptible to bacterial contamination. Specifically, the catheter essentially compromises the skin's natural protective barrier, providing a direct route to bypass the body's first line of immunity. In addition, upon insertion into the host, the outer surface of the catheter is quickly covered with host proteins that facilitate bacterial attachment and growth. There is also evidence that implanted abiotic material itself causes local attenuation of antimicrobial immune responses, thereby inhibiting a normal immune response against bacterial biofilm formation. Finally, patients who possess the greatest need for catheterization are often immunologically compromised and are therefore more susceptible to bacterial infection.
Catheters themselves are generally infected via one of two general routes, typically by microorganisms that compromise the natural flora surrounding the site of catheter insertion. For example, bacteria may contaminate the catheter along its outer surface, and it is believed that this type of infection often occurs during the initial insertion of the catheter through the skin. Catheters can also be contaminated in their lumenal compartments where fluids flow from contaminated infusate solutions. The most prevalent bacteria found to be the cause of bacterial sepsis are from the exterior flora surrounding the insertion site.
Catheter-related bloodstream infections are notoriously difficult to treat via conventional antibiotic therapy, with associated mortality rates ranging from 12% to 25%. Catheter related bloodstream infection is the most frequent serious complication seen with catheters with infections occurring in as many as 3% to 7% of all catheter placements, which is estimated to affect more than 250,000 patients in U.S. hospitals each year. In addition, these infection complications extend hospital stays, necessitate active intervention on the part of healthcare personnel, and result in driving the estimated annual domestic healthcare cost associated with complications arising from these catheter-related infections to more than nine billion dollars.
The use of a wound covering (sometimes referred to as a “dressing” or “wound dressing”) in conjunction with a catheter is conventional but does not entirely obviate the underlying infection risk as evidenced by the statistics above. Such wound dressings are typically placed proximate the catheter injection site and contact fluids exuding from that site.
Still further, other wounds such as burns, abrasions, surgical incisions, and the like are particularly susceptible to infection. In hospital settings, infections caused by antibiotic resistant bacteria such as Staphylococcus is a major concern and a cause of morbidity.
Therefore, a need exists for methods and medical devices and wound coverings for the detection of bacterial growth contamination in or about a wound that can readily detect and indicate the presence of microorganisms well before the infection has progressed to the point that it manifests itself by skin redness.